2. Progress at the large scale CO2 system,
Contents
Progress at the large scale CO2 system,
Results of the small scale CO2 system in the cryolab.

3. CO2 - Large scale system
Joao Noite,
Lukasz Zwalinski,
Torsten Koettig

4. CO2 - Large scale system

5. CO2 - Large scale system

6. CO2 - Large scale system
Location in 158:
- Commissioning of the system at 25°C,
Possible mass flow rate g/s,
Run only at ambient temperature
at the moment,
Next step => accumulator to vary Tsat.
Joao Noite, Lukasz Zwalinski, Torsten Koettig

7. Small scale system in the cryolab CERN:
CO2 – Small scale system
Small scale system in the cryolab CERN:
Test section length: 300 mm, heated part: 150 mm
Measurement of the heat transfer coefficient and pressure drop under variation of the following dependencies:
Vapor quality x
Heat flux q
Mass flux G
Saturation temperature Tsat
Jihao Wu, Daniel Helmer

8. CO2 - Small scale system
Heat transfer coefficient in the flow map (Tsat=263 K, G=300 kg/m2s, q=15kW/m2)

9. Pressure drop in the flow map (Tsat=263 K, G=300 kg/m2s, q=15kW/m2)
CO2 - Scanning the two-phase region
Pressure drop in the flow map (Tsat=263 K, G=300 kg/m2s, q=15kW/m2)
Pressure drop [mbar]
Mass flux [kg/m2s]
Vapor quality x

10. Saturation temperature Tsat
CO2 - Scanning the two-phase region
Measurement of the heat transfer coefficient and pressure drop under variation of the following dependencies:
Vapor quality x
Heat flux q
Mass flux G
Saturation temperature Tsat

11. Heat flux dependency of the heat coefficient (T=263 K, G=400 kg/m2s)
CO2 - Scanning the two-phase region
Heat flux dependency of the heat coefficient (T=263 K, G=400 kg/m2s)

12. Heat flux dependency of the pressure drop(T=263 K, G=400 kg/m2s)
CO2 - Scanning the two-phase region
Heat flux dependency of the pressure drop(T=263 K, G=400 kg/m2s)

13. Saturation temperature Tsat
CO2 - Scanning the two-phase region
Measurement of the heat transfer coefficient and pressure drop under variation of the following dependencies:
Vapor quality x
Heat flux q
Mass flux G
Saturation temperature Tsat

14. Mass flux dependency of the heat coefficient (T=263 K, q=7.5 kW/m2)
CO2 - Scanning the two-phase region
Mass flux dependency of the heat coefficient (T=263 K, q=7.5 kW/m2)

15. Mass flux dependency of the pressure drop (T=263 K, q=7.5 kW/m2)
CO2 - Scanning the two-phase region
Mass flux dependency of the pressure drop (T=263 K, q=7.5 kW/m2)

16. Saturation temperature Tsat
CO2 - Scanning the two-phase region
Measurement of the heat transfer coefficient and pressure drop under variation of the following dependencies:
Vapor quality x
Heat flux q
Mass flux G
Saturation temperature Tsat

17. CO2 - Scanning the two-phase region
Temperature dependency of the heat coefficient (q=15 kW/m2, G=300 kg/m2s)

18. Temperature dependency of pressure drop (q=15 kW/m2, G=300 kg/m2s)
CO2 - Scanning the two-phase region
Temperature dependency of pressure drop (q=15 kW/m2, G=300 kg/m2s)

19. Paper will be submitted to Int. Journal of Heat and Mass Transfer
Resume
Reliable test setup to determine heat transfer and pressure drop,
Measurements in the whole two phase region are done,
Influences of mass flux, heat flux and saturation temperature.
Paper will be submitted to
Int. Journal of Heat and Mass Transfer

20. CO2 - Small scale system Instabilities
Observed instabilities:
J-T expansion into subcooled liquid or x<3%
oscillations occur
Oscillations are amplified reaching the dryout at around 75 % vapor quality
Temperatures below -34 °C